[PATCH 3.4 05/91] drm/vmwgfx: Fix a potential infinite spin waiting for fifo idle

From: lizf
Date: Thu Nov 27 2014 - 04:25:29 EST


From: Thomas Hellstrom <thellstrom@xxxxxxxxxx>

3.4.105-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit f01ea0c3d9db536c64d47922716d8b3b8f21d850 upstream.

The code waiting for fifo idle was incorrect and could possibly spin
forever under certain circumstances.

Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
Reported-by: Mark Sheldon <markshel@xxxxxxxxxx>
Reviewed-by: Jakob Bornecrantz <jakob@xxxxxxxxxx>
Reivewed-by: Mark Sheldon <markshel@xxxxxxxxxx>
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
index a0c2f12..decca82 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fifo.c
@@ -163,8 +163,9 @@ void vmw_fifo_release(struct vmw_private *dev_priv, struct vmw_fifo_state *fifo)

mutex_lock(&dev_priv->hw_mutex);

+ vmw_write(dev_priv, SVGA_REG_SYNC, SVGA_SYNC_GENERIC);
while (vmw_read(dev_priv, SVGA_REG_BUSY) != 0)
- vmw_write(dev_priv, SVGA_REG_SYNC, SVGA_SYNC_GENERIC);
+ ;

dev_priv->last_read_seqno = ioread32(fifo_mem + SVGA_FIFO_FENCE);

--
1.9.1

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